This invention relates generally to gas lighters of the type having a tank and a filler valve and particularly to such lighters having a valve head biased by a spring and urged against a seal surface.
Such gas lighters are well known in the art. During the filling position of the lighter the valve housing extends from the upper cover wall into the interior space of the tank so that a portion of the space of the tank is disposed above the lower edge of the valve housing which is usually identical with the seal surface.
It would be desirable to maintain this portion of the interior space of the tank free of the liquified gas so that a gas buffer exists in this space which permits an expansion of the liquid gas under the influence of increased temperatures.
Even if such a gas buffer could be formed there is no guarantee that this buffer is sufficiently large. Due to reasons which will be more fully explained hereinafter the size of the gas buffer immediately after the filling process depends from that dimension H by which the valve housing extends into the space of the tank. This dimension H in the past has been selected arbitrarily or solely for reason of construction details of the filler valve and has not been determined by the geometry of the tank. If the dimension H is too small it cannot be excluded that during elevated ambient temperatures an intolerable high hydrostatic pressure builds up.
Independently from these causes it has been found that while utilizing those gases which are suitable for gas lighters that it is possible to fill this portion of the space of the tank which has just been defined up to a minute gas bubble with the liquid gas. Accordingly, there is practically no space left for an expansion of the fuel. The result is that even for a small increase of temperature a considerable hydrostatic pressure builds up in the tank which can lead to a destruction of the tank. The danger of a temperature increase for a completely filled gas lighter is particularly large because the lighter may, for example, be carried in a pants pocket or may be left in an automobile, the interior of which may assume rather high temperature due to sunlight.
It is accordingly an object of the present invention to provide a gas lighter of the type discussed which prevents the creation of an undesirable high hydrostatic pressure in the tank of the lighter.